Channel feedback reporting for shared frequency spectrum

ABSTRACT

Methods, systems, and devices are described for wireless communication. A device may use enhanced reporting mechanisms to support control information reporting on shared spectrum. In some cases, a device may utilize enhanced component carriers (eCCs) for data transmissions. In one example, the device may transmit control information (e.g., ACK/NACK, CSI, etc.) to a corresponding device using a CCA exempt transmission (CET). In another example, a device may report control information quasi-periodically. For instance, a device may be assigned a specified interval and a control feedback window for reporting control information (e.g., CSI). The window may provide a duration prior and subsequent to the specified interval during which a UE may transmit control information. For example, the device may perform a CCA reserving the channel for a duration that does not include the specified interval but may transmit feedback information based on determining the specified interval falls within the assigned window.

CROSS REFERENCES

The present Application for Patent claims priority to U.S. ProvisionalPatent Application No. 62/158,412 by Yoo et al., entitled “ChannelFeedback Reporting for CCs,” filed May 7, 2015, assigned to the assigneehereof.

BACKGROUND

1. Field of Disclosure

The following relates generally to wireless communication, and morespecifically to channel feedback reporting for shared frequencyspectrum.

2. Description of Related Art

Wireless communication systems are widely deployed to provide varioustypes of communication content such as voice, video, packet data,messaging, broadcast, and so on. These systems may be multiple-accesssystems capable of supporting communication with multiple users bysharing the available system resources (e.g., time, frequency, andpower). Examples of such multiple-access systems include code-divisionmultiple access (CDMA) systems, time-division multiple access (TDMA)systems, frequency-division multiple access (FDMA) systems,single-carrier frequency-division multiple access (SC-FDMA) systems, andorthogonal frequency-division multiple access (OFDMA) systems.

By way of example, a first wireless multiple-access communication systemmay operate according to a radio access technology (RAT), such as LIE,and may include a number of base stations, each simultaneouslysupporting communication for multiple communication devices, otherwiseknown as user equipments (UEs). A base station may communicate with UEson downlink channels (e.g., for transmissions from a base station to aUE) and uplink channels (e.g., for transmissions from a UE to a basestation). A second wireless multiple-access communications system mayoperate according to a different RAT, such as Wi-Fi, and may include anumber of base stations or access points (APs), each simultaneouslysupporting communication for multiple mobile devices or stations (STAs).APs may communicate with STAs on downstream and upstream links. In somecases both types of communication systems may operate in the presence ofone another and may use shared resources.

In a wireless local area network (WLAN), such as Wi-Fi, an AP maycommunicate with multiple STAs over a shared radio frequency spectrum.The STAs may use contention procedures that include communicating one ormore control frames prior to establishing a communication link, suchthat confirmation of the communication link via exchange of controlframes limits interference experienced by nearby communication devices.One example of such techniques include Request to Send (RTS) and Clearto Send (CTS) messaging, where, for example, a STA looking tocommunicate with another device (e.g., another STA or AP), may firstsend an RTS frame to the device. Once the recipient device receives theRTS frame, the recipient device may confirm the communication link bysending a CTS frame. After the CTS frame is received by the STA, the STAmay then begin transmitting data to the recipient device. In this way,RTS/CTS messaging can reduce frame collisions by enabling a device, suchas a STA or AP, to in essence clear the communication path beforetransmitting data to an AP or STA.

In an LIE network, a base station and a UE may communicate over adedicated frequency spectrum or over different frequency bands of theradio frequency spectrum (e.g., a dedicated radio frequency band and ashared radio frequency band) of a cellular network. With increasing datatraffic in cellular networks that use a dedicated (e.g., licensed) radiofrequency band, offloading of at least some data traffic to a shared(e.g., unlicensed) radio frequency spectrum may provide a cellularoperator with opportunities for enhanced data transmission capacity. Ashared radio frequency spectrum may also provide service in areas whereaccess to a dedicated radio frequency spectrum is unavailable. An LTEdevice that is configured for operation in shared frequency spectrum maybe considered to be an LTE-Unlicensed (LTE-U) device. An LTE-U devicemay be configured for operation in dedicated radio frequency spectrum,using a standalone carrier in shared radio frequency spectrum, or usingshared radio frequency spectrum in addition to dedicated radio frequencyspectrum.

Prior to gaining access to and communicating over a shared radiofrequency spectrum, a base station or UE may perform a listen beforetalk (LBT) procedure to contend for access to the shared radio frequencyspectrum. This LBT procedure may be compatible with contentionprocedures used by Wi-Fi devices to gain access to the shared radiofrequency spectrum. An LBT procedure may include performing a clearchannel assessment (CCA) procedure to determine whether a channel of theshared radio frequency spectrum is available. Since a UE or base stationfirst monitors the channel during the CCA to detect if the channel isoccupied, a UE or base station may not win control of the channel witheach LBT procedure

In some cases, a device, such as an LTE/LTE-U UE, may report controlinformation (e.g. acknowledgement (ACK)/negative ACK (NACK), channelstate information (CSI), etc.) periodically or aperiodically to acorresponding LTE/LTE-U base station. For periodic reporting, the UE maysend the control information according to an interval, specified by thebase station, while for aperiodic reporting the UE may send controlinformation in response to receiving a trigger from the base station.However, as mentioned above, the UE may fail to win control of thechannel after performing an LBT procedure for periods corresponding tothe designated interval. Therefore, the UE may fail to transmit controlinformation to the base station under various circumstances. In the caseof aperiodic reporting, the UE may fail to report the controlinformation until the UE performs a successful LBT procedure. Delayed orfailed control feedback reports may prevent the network from developingcurrent channel estimates resulting in decreased link performance orthroughput.

SUMMARY

A device may use enhanced reporting mechanisms to support controlinformation reporting on shared spectrum. In some cases, a device mayutilize enhanced component carriers (eCCs) for data transmissions. Inone example, the device may transmit control information (e.g.,ACK/NACK, CSI, etc.) to a corresponding device using a CCA exempttransmission (CET). In another example, a device may report controlinformation quasi-periodically. For example, a UE may be configured witha specified periodic CSI reporting interval and a control feedbackwindow. While the periodic CSI reporting interval may designate aparticular TTI for reporting periodic CSI, the control feedback windowmay provide a duration prior or subsequent to the designated TTI duringwhich the UE may transmit control information. For example, the UE mayperform an LBT procedure to gain access to the channel and transmit theperiodic CSI report at the beginning of a control feedback window thatis within a certain time period of, or includes, the designatedreporting TTI. The LBT procedure may include multiple attempts toperform a CCA procedure to reserve the channel for transmitting theperiodic CSI feedback.

A method of wireless communication is described. The method may includecommunicating with an eNB over a frequency channel of a shared frequencyband, receiving a data transmission from the eNB over the frequencychannel of the shared frequency band, determining ACK/NACK informationfor the data transmission, and transmitting the ACK/NACK information ina clear channel assessment (CCA) exempt feedback transmission to the eNBover the frequency channel of the shared frequency band, wherein theACK/NACK information is mapped to designated resources of an uplinkcontrol channel structure for the CCA-exempt feedback transmission.

An apparatus for wireless communication is described. The apparatus mayinclude means for communicating with an eNB over a frequency channel ofa shared frequency band, means for receiving a data transmission fromthe eNB over the frequency channel of the shared frequency band, meansfor determining ACK/NACK information for the data transmission, andmeans for transmitting the ACK/NACK information in a CCA exempt feedbacktransmission to the eNB wherein the ACK/NACK information is mapped todesignated resources of an uplink control channel structure for theCCA-exempt feedback transmission.

A further apparatus for wireless communication is described. Theapparatus may include a processor, memory in electronic communicationwith the processor, and instructions stored in the memory and operable,when executed by the processor, to cause the apparatus to communicatewith an eNB using a frequency channel of a shared frequency band,receive a data transmission from the eNB over the frequency channel ofthe shared frequency band, determine ACK/NACK information for the datatransmission, and transmit the ACK/NACK information in a CCA exemptfeedback transmission to the eNB via the frequency channel of the sharedfrequency band, wherein the ACK/NACK information is mapped to designatedresources of an uplink control channel structure for the CCA-exemptfeedback transmission.

A non-transitory computer-readable medium storing code for wirelesscommunication is described. The code may include instructions executableto communicate with an eNB using a frequency channel of a sharedfrequency band, receive a data transmission from the eNB over thefrequency channel of the shared frequency band, determine ACK/NACKinformation for the data transmission, and transmit the ACK/NACKinformation in a CCA exempt feedback transmission to the eNB via thefrequency channel of the shared frequency band, wherein the ACK/NACKinformation is mapped to designated resources of an uplink controlchannel structure for the CCA-exempt feedback transmission.

Some examples of the method, apparatuses, or non-transitorycomputer-readable medium described herein may further include processes,features, means, or instructions for determining uplink schedulingfeedback or channel state information (CSI) feedback, and transmitting,in the CCA-exempt feedback transmission, the uplink scheduling feedbackor the CSI feedback. Additionally or alternatively, some examples mayinclude processes, features, means, or instructions for determining atarget modulation and coding scheme (MCS) for a subsequent datatransmission based at least in part on channel measurements of one ormore reference signals associated with the current data transmission,and the transmitted CSI feedback comprises an indicator associated withthe target MCS.

Some examples of the method, apparatuses, or non-transitorycomputer-readable medium described herein may further include processes,features, means, or instructions for identifying a current MCS for thedata transmission, determining a channel quality delta between thecurrent MCS and the target MCS, and the indicator associated with thetarget MCS comprises the channel quality delta. Additionally oralternatively, in some examples the one or more reference signalscomprise any of a cell-specific reference signals (CRS), a demodulationreference signal (DM-RS), a UE-specific reference signal (UE-RS), orcombinations thereof.

In some examples of the method, apparatuses, or non-transitorycomputer-readable medium described herein, the determining the targetMCS for the subsequent data transmission comprises estimating a qualityof a channel from the eNB based at least in part on the CRS and anidentified precoding matrix for the current data transmission. In someexamples, the uplink control channel structure comprises a subset offrequency resources of the frequency channel of the shared frequencyband. Additionally or alternatively, in some examples the start of theCCA-exempt feedback transmission occurs less than a predetermined CCAtime period from an end of the data transmission.

In some examples of the method, apparatuses, or non-transitorycomputer-readable medium described herein, the frequency channel of theshared frequency band comprises an eCC configured for the UE in astandalone operation mode. Additionally or alternatively, some examplesmay include processes, features, means, or instructions for receiving afeedback configuration for providing feedback for transmissions via thefrequency channel of the shared frequency band, wherein the feedbackconfiguration indicates providing the feedback in the CCA-exemptfeedback transmission, a CCA-compliant feedback transmission, orcombinations thereof.

A method of wireless communication is described. The method may includeidentifying a transmission time interval (TTI) associated withtransmitting first CSI feedback for a CC operating in a standaloneoperation mode over a shared frequency band based at least in part on aCSI feedback configuration, identifying a transmission, from the eNB,reserving one or more channels of the shared frequency band forcommunication via the CC, the transmission identifying a time divisionduplex (TDD) configuration for the CC over a specified time duration,determining an uplink transmission window of one or more uplinktransmission windows during the specified time duration for transmittingthe first CSI feedback based at least in part on a timing characteristicof the uplink transmission window relative to the identified TTI, andperforming a CSI feedback transmission procedure to transmit the firstCSI feedback during the uplink transmission window.

An apparatus for wireless communication is described. The apparatus mayinclude means for identifying a TTI associated with transmitting firstCSI feedback for a CC operating in a standalone operation mode over ashared frequency band based at least in part on a CSI feedbackconfiguration, means for identifying a transmission, from the eNB,reserving one or more channels of the shared frequency band forcommunication via the CC, the transmission identifying a TDDconfiguration for the CC over a specified time duration, means fordetermining an uplink transmission window of one or more uplinktransmission windows during the specified time duration for transmittingthe first CSI feedback based at least in part on a timing characteristicof the uplink transmission window relative to the identified TTI, andmeans for performing a CSI feedback transmission procedure to transmitthe first CSI feedback during the uplink transmission window.

A further apparatus for wireless communication is described. Theapparatus may include a processor, memory in electronic communicationwith the processor, and instructions stored in the memory and operable,when executed by the processor, to cause the apparatus to identify a TTIassociated with transmitting first CSI feedback for a CC operating in astandalone operation mode over a shared frequency band based at least inpart on a CSI feedback configuration, identify a transmission, from theeNB, reserving one or more channels of the shared frequency band forcommunication via the CC, the transmission identifying a TDDconfiguration for the CC over a specified time duration, determine anuplink transmission window of one or more uplink transmission windowsduring the specified time duration for transmitting the first CSIfeedback based at least in part on a timing characteristic of the uplinktransmission window relative to the identified TTI, and perform a CSIfeedback transmission procedure to transmit the first CSI feedbackduring the uplink transmission window.

A non-transitory computer-readable medium storing code for wirelesscommunication is described. The code may include instructions executableto identify a TTI associated with transmitting first CSI feedback for aCC operating in a standalone operation mode over a shared frequency bandbased at least in part on a CSI feedback configuration, identify atransmission, from the eNB, reserving one or more channels of the sharedfrequency band for communication via the CC, the transmissionidentifying a TDD configuration for the CC over a specified timeduration, determine an uplink transmission window of one or more uplinktransmission windows during the specified time duration for transmittingthe first CSI feedback based at least in part on a timing characteristicof the uplink transmission window relative to the identified TTI, andperform a CSI feedback transmission procedure to transmit the first CSIfeedback during the uplink transmission window.

In some examples of the method, apparatuses, or non-transitorycomputer-readable medium described herein, the CSI feedback transmissionprocedure comprises performing a first CCA-compliant feedbacktransmission procedure over the one or more channels during a firstuplink TTI of the uplink transmission window. Additionally oralternatively, in some examples the CSI feedback transmission procedurecomprises transmitting the first CSI feedback upon a successfulreservation of the one or more channels based at least in part on thefirst CCA-compliant feedback transmission procedure.

In some examples of the method, apparatuses, or non-transitorycomputer-readable medium described herein, the CSI feedback transmissionprocedure comprises determining that the one or more channels are busyduring the first uplink TTI based at least in part on the firstCCA-compliant feedback transmission procedure, and the CSI feedbacktransmission procedure comprises performing a second CCA-compliantfeedback transmission procedure over the one or more channels during asecond, subsequent uplink TTI of the uplink transmission window.Additionally or alternatively, some examples may include processes,features, means, or instructions for identifying a discovery referencesignal (DRS) configuration for the CC, the DRS configuration indicatinga cyclical transmission pattern for reference signals transmitted in theone or more channels, and performing channel measurements for the one ormore channels based at least in part on the cyclical transmissionpattern.

In some examples of the method, apparatuses, or non-transitorycomputer-readable medium described herein, the first CSI feedbackcomprises a wideband channel quality for a frequency range spanning theone or more channels. Additionally or alternatively, in some examplesthe timing characteristic comprises the uplink transmission window beingwithin a time threshold of the identified TTI.

In some examples of the method, apparatuses, or non-transitorycomputer-readable medium described herein, the timing characteristiccomprises the uplink transmission window including the identified TTI.

Some examples of the methods, apparatuses, or non-transitorycomputer-readable media described herein may further include processes,features, means, or instructions for channel feedback reporting for CCs(e.g., eCC in standalone operation, etc.) . Further scope of theapplicability of the described systems, methods, apparatuses, orcomputer-readable media will become apparent from the following detaileddescription, claims, and drawings. The detailed description and specificexamples are given by way of illustration only, since various changesand modifications within the scope of the description will becomeapparent to those skilled in the art.

BRIEF DESCRIPTION OF THE DRAWINGS

A further understanding of the nature and advantages of the presentdisclosure may be realized by reference to the following drawings. Inthe appended figures, similar components or features may have the samereference label. Further, various components of the same type may bedistinguished by following the reference label by a dash and a secondlabel that distinguishes among the similar components. If just the firstreference label is used in the specification, the description isapplicable to any one of the similar components having the same firstreference label irrespective of the second reference label.

FIG. 1 illustrates an example of a wireless communications system thatsupports channel feedback reporting for component carriers (CCs) (e.g.,eCC in standalone operation, etc.) in accordance with various aspects ofthe present disclosure.

FIG. 2 illustrates an example of a wireless communication subsystem forchannel feedback reporting for CCs (e.g., eCC in standalone operation,etc.) in accordance with various aspects of the present disclosure.

FIG. 3A illustrates an example of an eCC transmission scheme for channelfeedback reporting for CCs (e.g., eCC in standalone operation, etc.) inaccordance with various aspects of the present disclosure.

FIG. 3B illustrates an example of an eCC uplink transmission for channelfeedback reporting for CCs (e.g., eCC in standalone operation, etc.) inaccordance with various aspects of the present disclosure.

FIG. 4A and 4B illustrate examples of an eCC fast feedback transmissionscheme for channel feedback reporting for CCs (e.g., eCC in standaloneoperation, etc.) in accordance with various aspects of the presentdisclosure.

FIGS. 5-7 show block diagrams of a wireless device that supportsfeedback reporting for eCCs in accordance with various aspects of thepresent disclosure.

FIG. 8 illustrates a block diagram of a system including a device thatsupports feedback reporting for eCCs in accordance with various aspectsof the present disclosure.

FIG. 9 illustrates a block diagram of a system including a base stationthat supports feedback reporting for eCCs in accordance with variousaspects of the present disclosure.

FIGS. 10-12 illustrate methods for channel feedback reporting for CCs(e.g., eCC in standalone operation, etc.) in accordance with variousaspects of the present disclosure.

DETAILED DESCRIPTION

According to the present disclosure, a device may use enhanced reportingmechanisms to support control information reporting on shared spectrum.Aspects of the disclosure are described in the context of a wirelesscommunication system. For example, a UE may be configured forcommunication with a base station via an LTE/LTE-A component carrier(e.g., enhanced component carrier (eCC), etc.) operating in a standalonemode in an unlicensed or shared frequency spectrum band. UnlikeLTE/LTE-A operation in licensed frequency bands, reporting of CSI (e.g.,periodic, aperiodic, etc.) for unlicensed or shared bands may beconditional on a base station gaining access to the channel in a listenbefore talk (LBT) procedure, allocating uplink subframes, and the UEsuccessfully gaining access to the channel in an LBT procedure. A UEoperating in licensed band may be allocated control channel resourcesfor transmission of periodic CSI according to a periodic CSI reportingschedule. A UE reporting periodic CSI via a standalone CC or eCC inshared spectrum may not be able to transmit the CSI in transmission timeintervals (TTIs) corresponding to the periodic reporting interval. Inembodiments, the UE reports CSI quasi-periodically via a frequencychannel of a shared frequency band based on a periodic reportingschedule and control feedback window. As used herein, a shared frequencyband may refer to a frequency band within an unlicensed or sharedspectrum (e.g., licensed to multiple operators or a prioritizedoperator). The UE may perform an LBT procedure to gain access to thechannel to transmit the periodic CSI report at the beginning of thecontrol feedback window, if the window is within a certain time periodof, or includes, the designated reporting TTI. The LBT procedure mayinclude multiple attempts to perform a clear channel assessment (CCA)procedure to reserve the channel for transmitting the quasi-periodic CSIfeedback.

Aperiodic CSI reports may also be triggered for a UE communicating witha base station via a standalone CC or eCC in shared spectrum. Unlike inlicensed spectrum, reference signals may not be present onsemi-statically configured periodic time-frequency locations for a CC oreCC in shared spectrum. In embodiments, reference signals fordetermining aperiodic CSI are dynamically configured for subframes wherean aperiodic CSI request is sent to the UE. Presence of referencesignals (e.g., CRS, UE-RS, CSI-RS, etc.) may be signaled in the DLgrants for UEs with scheduled DL resources for the subframe so thatother, non-CSI triggered UEs are able to do proper PDSCH rate matchingaround the reference signals. The aperiodic CSI may be computed based onthe latest received reference signal, which may be the reference signalsin the DL burst with the aperiodic CSI trigger, or for a channel wherethe base station could not clear the channel using CCA, the latestinstance of reference signals according to a discovery reference signal(DRS) configuration.

Additionally or alternatively, a UE may utilize a fast feedbackreporting scheme in which the device transmits control information(e.g., ACK/NACK, CSI, etc.) mapped to a control channel structure in aCCA exempt transmission (CET) following reception of a DL datatransmission. The CSI may be determined based on reference signals(e.g., CRS with indicated precoding, DM-RS, etc.) in the DL datatransmission. The CSI may include CQI reporting for fast linkadaptation, which may be reported in the form of a delta CQI. The UE maybe semi-statically configured to report fast feedback, regular feedbackusing PUCCH or PUSCH resources, or both fast feedback and regularfeedback. These and other aspects of the disclosure are furtherillustrated by and described with reference to apparatus diagrams,system diagrams, and flowcharts.

FIG. 1 illustrates an example of a wireless communications system 100that supports feedback reporting for eCCs in accordance with variousaspects of the present disclosure. The wireless communications system100 includes base stations 105, UEs 115, APs 150, STAs 155, and a corenetwork 130. In some examples, the wireless communications system 100may be a Long Term Evolution (LTE)/LTE-Advanced (LTE-A) network.

The base stations 105 may wirelessly communicate with the UEs 115 viaone or more base station antennas. Each of the base stations 105 mayprovide communication coverage for a respective geographic coverage area110. The communication links 125 shown in wireless communications system100 may include uplink (UL) transmissions from a UE 115 to a basestation 105, or downlink (DL) transmissions, from a base station 105 toa UE 115. The base stations 105 may support, and may communicate withone another to fast recovery procedures. For example, the base stations105 may interface with the core network 130 through backhaul links 132(e.g., S1, etc.). The base stations 105 may also communicate with oneanother over backhaul links 134 (e.g., X1, etc.) either directly orindirectly (e.g., through core network 130). The base stations 105 mayperform radio configuration and scheduling for communication with theUEs 115, or may operate under the control of a base station controller(not shown). In various examples, base stations 105 may be macro cells,small cells, hot spots, or the like. The base stations 105 may also bereferred to as eNodeBs (eNBs) in some examples.

The UEs 115 may be dispersed throughout the wireless communicationssystem 100, and each UE 115 may be stationary or mobile. A UE 115 mayalso be referred to as a mobile station, a subscriber station, a remoteunit, a wireless device, an access terminal, a handset, a user agent, aclient, or some other suitable terminology. A UE 115 may also be acellular phone, a wireless modem, a handheld device, a personalcomputer, a tablet, a personal electronic device, a machine typecommunication (MTC) device or the like. The UEs 115 may communicate withbase stations 105, and may support fast recovery procedures.

A UE may be configured with multiple carriers in carrier aggregation(CA) configuration, and the communication links 125 may represent suchmulticarrier CA configurations. A carrier may also be referred to as acomponent carrier (CC), a layer, a channel, etc. The term “componentcarrier” may refer to each of the multiple carriers utilized by a UE inCA operation, and may be distinct from other portions of systembandwidth. For instance, a CC may be a relatively narrow-bandwidthcarrier susceptible of being utilized independently or in combinationwith other component carriers. Each CC may provide the same capabilitiesas an isolated carrier based on release 8 or release 9 of the L ILstandard. Multiple component carriers may be aggregated or utilizedconcurrently to provide some UEs 115 with greater bandwidth and, e.g.,higher data rates. Thus, individual CC may be backwards compatible withlegacy UEs 115 (e.g., UEs 115 implementing LTE release 8 or release 9);while other UEs 115 (e.g., UEs 115 implementing post-release 8/9 LTEversions), may be configured with multiple component carriers in amulti-carrier mode. A carrier used for DL may be referred to as a DL CC,and a carrier used for UL may be referred to as an UL CC. A UE 115 maybe configured with multiple DL CCs and one or more UL CCs for carrieraggregation. Each carrier may be used to transmit control information(e.g., reference signals, control channels, etc.), overhead information,data, etc.

A UE 115 may communicate with a single base station 105 utilizingmultiple carriers, and may also communicate with multiple base stations105 simultaneously on different carriers. Each cell of a base station105 may include an UL CC and a DL CC. The coverage area 110 of eachserving cell for a base station 105 may be different (e.g., CCs ondifferent frequency bands may experience different path loss). In someexamples, one carrier is designated as the primary carrier, or primarycomponent carrier (PCC), for a UE 115, which may be served by a primarycell (PCell). Primary cells may be semi-statically configured by higherlayers (e.g., radio resource control (RRC), etc.) on a per-UE basis.Certain uplink control information (UCI), e.g., ACK/NACK, channelquality indicator (CQI), and scheduling information transmitted onphysical uplink control channel (PUCCH), are carried by the primarycell. Additional carriers may be designated as secondary carriers, orsecondary component carriers (SCC), which may be served by secondarycells (SCells). Secondary cells may likewise be semi-staticallyconfigured on a per-UE basis. In some cases, secondary cells may notinclude or be configured to transmit the same control information as theprimary cell.

In some cases, wireless communications system 100 may utilize one ormore enhanced component carriers (eCCs). An enhanced component carrier(eCC) may be characterized by one or more features including: widerbandwidth, shorter symbol duration, shorter transmission time interval(TTIs), and modified control channel configuration. In some cases, aneCC may be associated with a carrier aggregation (CA) configuration or adual connectivity configuration (e.g., when multiple serving cells havea suboptimal backhaul link). An eCC may also be configured for use inunlicensed spectrum or shared spectrum (e.g., where more than oneoperator is allowed to use the spectrum). An eCC characterized by widebandwidth may include one or more segments that may be utilized by UEs115 that are not capable of monitoring the whole bandwidth or prefer touse a limited bandwidth (e.g., to conserve power). An eCC may utilizedynamic time division duplex (TDD) operation (i.e., it may switch fromdownlink (DL) to uplink (UL) operation for short bursts according todynamic conditions).

In some cases, an eCC may utilize a different symbol duration than othercomponent carriers (CCs), which may include use of a reduced symbolduration as compared with symbol durations of the other CCs. A shortersymbol duration is associated with increased subcarrier spacing. Adevice, such as a UE 115 or base station 105, utilizing eCCs maytransmit wideband signals (e.g., 20, 40, 60, 80 Mhz, etc.) at reducedsymbol durations (e.g., 16.67 μs).

In some examples, the wireless communications system 100 may operateaccording to a first radio access technology (e.g., a cellular radioaccess technology, such as an LTE/LTE-A technology), but operate in thepresence of one or more networks or nodes operating according to asecond radio access technology (e.g., a Wi-Fi technology). By way ofexample, FIG. 1 shows a network comprised of a Wi-Fi access point (AP)150 in communication with Wi-Fi stations (STAs) 155. In some examples, aUE 115 or base station 105 may be an LTE-U device that supportsoperation in shared bands used by Wi-Fi. LTE/LTE-U devices mayadditionally support eCC operation for transmission on licensed orunlicensed bands. A STA 155 or AP 150 may be Wi-Fi devices that maysupport LTE but may not be configured for LTE-U or eCC operation. In theinterest of clarity, LTE-U devices will be referred to as base stations105 or UEs 115, while non LIE-U devices will be referred to as APs 150or STAs 155.

Before transmitting over a shared channel, an LTE-U device, such as abase station 105 or UE 115, may perform an LBT procedure to win controlof the shared channel. An LBT procedure may include performing a CCA todetermine if the shared channel is available. If the device determinesthe channel is available, it may transmit a preamble (e.g., Wi-Fipreamble, channel usage beacon (CUBS), etc.) to alert other devices thatit is about to transmit over the channel. Otherwise, if the channel isnot available, the device may refrain from transmitting over thechannel. In certain cases, a device may transmit over a channel withoutobserving CCA protocol using a transmission that complies with variousCET rules. CET rules may include, for example, a maximum duration ormaximum percentage of time or frequency resources that can be used intransmissions without using a CCA procedure prior to transmission. Insome examples, CET rules include a maximum duty cycle of 5%.

An LTE-U device, such as a UE 115, may transmit CSI feedback informationto another LTE-U device (e.g., an eNB, etc.). The CSI may includechannel quality information (CQI), rank indication (RI), or a precodingmatrix indicator (PMI). This information may be used by the eNB todetermine a modulation and coding scheme (MCS), rank, precoding scheme,and the like. The CSI information may be reported, by the UE, eitherperiodically or aperiodically. For example, for periodic CSI reporting,a base station 105 may direct a UE 115 to report CSI information onallocated reporting resources according to a specified interval. In somecases, the reporting resources for periodic CSI reporting are unique ineither the time or frequency domain from CSI reporting resourcesspecified for other UEs 115 within the coverage area. The base station105 may expect a response from the UE 115 on the specified reportingresources and correlate information received during that interval withthe scheduled UE 115. For instance, the base station 105 may identify aUE 115 based on the time and frequency resources used to receive the CSIreport. In some cases, the periodic CSI information may be reportedusing physical uplink control channel (PUCCH) resources. For aperiodicreporting, a base station 105 may send a trigger to UE 115 that triggersUE 115 to report CSI information. After receiving the trigger, the UE115 may transmit the CSI information to the base station 105. In somecases, the aperiodic CSI report may be transmitted using physical uplinkshared channel (PUSCH) resources.

An LTE-U device, such as a base station 105 or UE 115, may utilize asingle CC in either dedicated spectrum or shared spectrum. In otherinstances, the LTE-U device may utilize multiple CCs, such as a PCC(e.g., associated with dedicated spectrum) and an SCC (e.g., associatedwith shared spectrum). In some cases, the LTE-U device may utilize oneor more eCCs or a combination of eCCs and CCs for transmissions. AnLTE-U device using multiple carriers may transmit CSI reports, for boththe primary and secondary CCs, on the primary CC using uplink resourcesallocated by a base station 105. An LTE-U device using a single CC or asingle eCC associated with shared spectrum may not be allocateddedicated uplink resources to transmit CSI resources. As mentionedabove, the LTE-U device may perform an LBT procedure before transmittingon a shared channel, and in some cases, may refrain from transmitting ifit is determined that the channel is occupied. Therefore, in the case ofperiodic reporting, the LTE-U device may fail to win the channel for aduration that includes the specified reporting interval and fail totransmit CSI information. In the case of aperiodic reporting, the LTE-Udevice may wait to transmit CSI information until the next successfulLBT procedure. Delayed or failed CSI feedback reports may prevent thenetwork from developing current channel estimates resulting in decreasedlink performance or throughput.

A UE 115 may use enhanced reporting mechanisms to support controlinformation reporting on shared spectrum. In some cases, the UE 115 mayutilize enhanced component carriers (eCCs) for data transmissions. Inone example, the UE 115 may transmit control information to a basestation 105 using a CET. For instance, the UE 115 may transmit ACK/NACKsto a base station 105 via the CET transmission. Additionally oralternatively, the UE 115 may transmit uplink scheduling feedback or CSIfeedback during the CET. In another example, a UE 115 may report controlinformation quasi-periodically. For instance, the UE 115 may receivescheduling for CSI reporting from a base station 105. The scheduling maydesignate, to the UE 115, specified intervals (e.g., specific TTI,subframe, etc.) and a control feedback window for reporting controlinformation (e.g., CSI). The window may provide a duration prior andsubsequent to the specified interval during which a UE 115 may transmitcontrol information. For example, the UE 115 may perform a CCA reservingthe channel for a duration that does not include the specified intervalbut may transmit feedback information based on determining the specifiedinterval falls within the assigned window. In some cases, the report maybe transmitted prior or subsequent to the scheduled interval.

FIG. 2 illustrates an example of a wireless communications subsystem 200for channel feedback reporting for shared frequency spectrum inaccordance with various aspects of the present disclosure. Channelfeedback reporting may include ACK/NACK and CSI reports. Wirelesscommunications subsystem 200 may include UE 115-a, UE 115-b, basestation 105-a, STA 155-a, and AP 150-a which may be examples of a UE 115base station 105, STA 155, or AP 150 described above with reference toFIG. 1. Base station 105-a may communicate with UEs 115-a and 115-b viacommunication links 205-a and 205-b, respectively, when UEs 115-a and115-b are within coverage area 110-a, while STA 155-a and AP 150-a maycommunicate with one another via communication link 205-c when STA 155-ais within coverage area 110-b as generally described above withreference to FIG. 1. Communication links 205-a, 205-b may use LTE/LTE-ACCs or eCCs operating over a same frequency band of unlicensed or sharedspectrum (e.g., in a standalone mode) as communication link 205-c.

In one example, base station 105-a may establish connections with UE115-a and UE 115-b. Base station 105-a may send CSI reportingconfiguration information to both UE 115-a and UE 115-b that indicates areporting schedule according to which UE 115-a and UE 115-b shouldreport control information (e.g., CSI, etc.) to base station 105-a. Basestation 105-a may additionally send a control feedback window to UE115-a and UE 115-b designating time thresholds prior and/or subsequentto specified reporting TTIs (e.g., subframes, symbols, etc.) for whichquasi-periodic CSI reporting is configured.

Base station 105-a may perform a successful CCA and begin transmittingon the downlink. The transmission may include a preamble to clear thechannel in addition to subsequent control and user data. The preamblemay include a preamble that indicates a downlink and uplinkconfiguration for subsequent TTIs to UE 115-a and UE 115-b. UE 115-a andUE 115-b may monitor the downlink transmission for incoming data and mayalso use received reference signals (RSs) (e.g., CRS, CSI-RS, UE-RS,etc.) to generate channel estimates and CSI feedback.

In some cases, both UE 115-a and UE 115-b may be scheduled to report atrespective TTIs within a time period of designated uplink TTIs. UE 115-aand UE 115-b may each perform CCA procedures in an attempt to win thechannel during the uplink TTIs. In some cases, the CCA for UE 115-a maybe successful and the CCA for UE 115-b may fail (e.g., upon initiationof the transmission by UE 115-a). After winning the channel, UE 115-amay transmit the CSI report during the first TTI following the CCA. Insome cases, the scheduled TTI assigned to UE 115-a for CSI reporting maybe prior or subsequent to the first TTI, but may fall within thedesignated window. After UE 115-a finishes reporting the CSI information(which may or may not be accompanied by transmission of other data), orafter the base station performs a second successful CCA and downlinktransmission, UE 115-b may be able to successfully perform a CCA. Uponthe successful CCA, UE 115-b may transmit CSI information to basestation 105-a. Although the CSI report may not be transmitted using theassigned TTI, base station 105-a may monitor for CSI transmissions fromUEs 115-a and 115-b during the uplink TTIs and may identify CSI reportsbased on UE-specific transmission information. For instance, basestation 105-a may identify CSI reports based on the frequency resources,MCS, or the sequence used for the transmission. The quasi-periodic CSItransmissions may be synchronous (e.g., aligned in time to the eCCsymbol periods) or asynchronous.

In another example, base station 105-a may configure UE 115-a and UE115-b for fast feedback reporting. In some cases, base station 105-a maytransmit a message, which may be included in a preamble, that enablesfast feedback of control information for UE 115-a and UE 115-b. Forinstance, base station 105-a may indicate to UE 115-a and UE 115-b toutilize CETs for control feedback. Base station 105-a may perform asuccessful CCA and transmit a preamble including transmissioninformation (e.g., duration, an UL-DL configuration for the transmissionresources, etc.) for the associated transmission. In some cases, thebase station 105-a may designate certain uplink symbols as CETresources. Each UE 115-a and UE 115-b may be designated distinctfrequency or time resources of a control channel structure for CETtransmissions (e.g., configured in the preamble, in RRC configuration,based on UE-ID, etc.). Base station 105-a may begin transmittingdownlink information to UEs within coverage area 110-a including UE115-a and UE 115-b. As mentioned above, the downlink transmission mayinclude reference signals for channel estimation. After the base station105-a finishes transmitting downlink information, UE 115-a and UE 115-bmay transmit control feedback (e.g., ACK/NACK, CSI) using CETs to basestation 105-a. In some cases, the control information for multiple UEs115 may be included within the same set of symbols (e.g., usingnon-overlapping or interleaved frequency resources, etc.) associatedwith a CET transmission. In other cases, UE 115-a may transmit in afirst set of CET symbols and UE 115-b may transmit in a second,subsequent set of CET symbols.

Base station 105-a may receive the fast feedback including CSI andACK/NACK reports. The CSI report may include CQI and/or delta CQI, whichmay be referenced to the MCS used by the base station 105-a for previousPDSCH transmission. The CSI may be generated using references signals(e.g., CRS with precoding applied or DM-RS) associated with the previousPDSCH. In some cases, the fast feedback may include PMI or RIindicators. Additionally or alternatively, UE 115-a or UE 115-b mayinclude CQI for regions outside of the decoded PDSCH. Base station 105-amay use fast feedback to adapt the MCS for subsequent DL transmissions.Fast feedback may enable wireless communications subsystem 200 toperform fast link adaptation and increase the throughput of the network.

In another example, a base station 105-a may send a request for anaperiodic CSI report from UE 115-a. In some examples, the report may betriggered by setting the CQI request field in an downlink controlinformation (DCI) message. The request may indicate a set of channels(e.g., one or more 20 MHz channels) for which UE 115 may generate a CSIreport. Unlike licensed spectrum where CRSs and/or CSI-RSs are presenton semi-statically configured periodic time and frequency locations,reference signals may only be dynamically available (e.g., based on thebase station clearing CCA, etc.). In some cases, base station 105-a maysend the CSI-RSs on demand, that is, base station 105-a sends theCSI-RSs only on the subframes in which base station 105-a sends theaperiodic feedback request. The base station 105-a may signal thepresence of CSI-RSs in downlink grants so that other UEs 115 may performPDSCH rate matching. For example, where the base station 105-a sends adata transmission to UE 115-b during a subframe which includes anaperiodic CSI request for UE 115-a, the base station 105-a may indicateto UE 115-b that CSI-RSs are present in the data transmission.

UE 115-a may compute CSI for the designated channels using thetransmitted CRSs or CSI-RSs. UE 115-a may transmit the aperiodic CSIreport to base station 105-a using the PUSCH. The CSI report may includeCSI for a set of channels (e.g., N*20 MHz) or a subset of the set ofchannels. The aperiodic CSI may be computed based on the latest receivedreference signal, which may be the reference signals in the DL burstwith the aperiodic CSI trigger, or for a channel where base station105-a could not clear the channel using CCA, the latest instance ofreference signals according to a discovery reference signal (DRS)configuration. In some cases, base station 105-a may transmit referencesignals using a common transmit power for narrow and widebandtransmissions. Therefore, the power spectral density (PSD) associatedwith the wider band transmission may be decreased when compared tonarrow band transmissions. In some cases, UE 115-a may determine the PSDof the reference signals based on the transmission bandwidth (e.g., 20,40, 60, 80 Mhz, etc.). In some cases, UE 115-a may develop a CSI reportbased on the determined PSD.

FIG. 3A illustrates an example of a transmission scheme 300-a forchannel feedback reporting for shared frequency spectrum in accordancewith various aspects of the present disclosure. Channel feedbackreporting may include ACK/NACK and CSI reports. Transmission scheme300-a may illustrate aspects of a communication session between a UE 115and a base station 105, as described above with reference to FIGS. 1-2.Transmission scheme 300-a may include CCA 305 performed by base station105, DL TTIs 310, and UL TTIs 315. DL TTIs 310 may include RSs 340.Periodic CSI reporting TTIs, CSI_UE1 320-a and CSI_UE2 320-b, may bedetermined according to periodic CSI configurations for a first UE 115and a second UE 115, respectively. The first and second UEs 115 may alsobe configured with quasi-periodic control feedback windows 325-a and325-b, respectively. The UL TTIs 315 may include scheduled CSI resources345 corresponding to the configured periodic CSI reporting intervals, insome cases.

In one example, base station 105 may transmit scheduling information toone or more UEs 115 indicating an interval where a UE 115 may transmitCSI. At a later point in time, the base station 105 may perform asuccessful CCA 305 and take control of a shared channel. The basestation 105 may then transmit a preamble reserving the channel andindicating an uplink and downlink configuration. The base station 105may begin DL TTIs 310 which may include RSs 340 (e.g., CRS, UE-RS,CSI-RS, etc.). The UEs 115 may use the RSs 340 to generate channelestimates and to develop CSI reports. One or more UEs 115 may bescheduled to transmit CSI feedback at periodic CSI reporting TTIs 320.

The first UE 115 may perform a successful CCA during quasi-periodiccontrol feedback window 325-a and transmit the CSI report. The CSIreport may be transmitted synchronously (e.g., aligned to one or moreTTIs following the CCA), or asynchronously, in some cases.

As mentioned above, because UEs 115 may perform an LBT procedure priorto transmitting uplink information during the UL TTIs 315, performingthe LBT procedure only for time periods associated with the scheduledCSI resources 345 may reduce the probability of winning the channel fora successful CSI feedback transmission. Thus, the UE 115 may fail totransmit the periodic CSI report for the particular periodic CSIinterval, despite the presence of available transmission resourcesearlier or later during UL TTIs 315. Therefore, a quasi-periodic controlfeedback window 325 may be configured to enable a UE 115 to transmitprior or subsequent to the scheduled periodic CSI reporting TTI 320. Inone case, a UE 115 may transmit CSI information in the first TTIfollowing a successful CCA. Initiating the LBT transmission procedure atthe beginning of configured UL TTIs 315 may significantly increase theprobability of a successful CCA for transmitting the CSI report duringUL TTIs 315. In one example, quasi-periodic control feedback windows maybe implicitly defined as all the uplink TTIs reserved by the basestation that contain the periodic CSI reporting TTI. In another example,quasi-periodic control feedback windows may be implicitly defined as allthe consecutive uplink TTIs reserved by the base station that containthe periodic CSI reporting TTI. In yet another example, quasi-periodiccontrol feedback windows may be implicitly defined by uplink TTIs(consecutive or non-consecutive) within a predetermined number of TTIsof the periodic CSI reporting TTI.

FIG. 3B illustrates an example of an uplink transmission 300-b forchannel feedback reporting for shared frequency spectrum in accordancewith various aspects of the present disclosure. Channel feedbackreporting may include ACK/NACK and CSI reports. Uplink transmission300-b may illustrate aspects of a communication session between a UE 115and a base station 105, as described above with reference to FIGS. 1-3A.Uplink transmission 300-b may include uplink TTIs 370. Uplink TTIs 370may include six uplink TTIs, including TTIs overlapping with periodicCSI reporting TTIs CSI_UE1 320-c and CSI_UE2 320-d. An expanded view ofUL TTIs 315-a may illustrate LBT channel feedback procedures formultiple UEs. The LBT procedure may include CCA_UE1 350-a and CCA_UE2350-b, which may be followed by CSI report 355-a and CSI report 355-b,respectively.

In one example, first and second UEs 115 (e.g., UE1 and UE2) may bescheduled to report CSI during uplink TTIs 370. The first UE 115 may bescheduled to report during uplink TTI K and the second UE 115 may bescheduled to report during uplink TTI K+2. Each UE 115 may determinethat its respective reporting interval CSI_UE1 320-c or CSI_UE2 320-c isscheduled within uplink TTIs 370. Accordingly, both UEs 115 may performa CCA in an attempt to win the channel. The first UE 115 may performsuccessful CCA_UE1 350-a may reserve the channel for a duration based onthe amount of data ready for transmission to base station 105. Based onidentifying that TTI K is within the quasi-periodic control feedbackwindow, the first UE 115 may transmit a CSI report 355-a in the TTIfollowing CCA_UE1 350-a. The first UE 115 may additionally transmitother data for the remainder of the channel reservation. In one example,uplink transmissions for the first UE 115 are complete after the CSIreport 355-a is sent and the channel is clear during clear channelinterval 360-a. During clear channel interval 360-a, other UEs 115,including the second UE 115, or STAs 110 may perform CCAs and beginuplink transmissions during busy channel interval 365-a. At a laterpoint in time, the second UE 115 may perform a successful CCA_UE2 350-b.In the following TTI, the second UE 115 may transmit CSI report 355-b,which may be prior to, subsequent to, or during TTI K+2. The remainderof the uplink TTIs 370 may be used by other UEs 115 for uplinktransmissions.

FIG. 4A illustrates an example of a fast feedback transmission scheme400-a for channel feedback reporting for CCs (e.g., eCC in standaloneoperation, etc.) in accordance with various aspects of the presentdisclosure. Channel feedback reporting may include ACK/NACK, uplinkscheduling information, and CSI reports. Fast feedback transmissionscheme 400-a may illustrate aspects of a communication session between aUE 115 and a base station 105, as described above with reference toFIGS. 1-3B. Fast feedback transmission scheme 400-a may include a CCA405, DL data transmission 410, and UL control channel transmission 415.The UE 115 may generate ACK/NACK information 425 for data received on DLdata transmission 410 and may include the ACK/NACK information 425 in ULcontrol channel transmission 415. The DL data transmission 410 mayinclude RSs 420 which may be used by the UE 115 to generate a CSI report430. Optionally, the CSI report 430 may also be included in UL controlchannel transmission 415.

In one example, a base station 105 may perform a successful CCA 405 andtransmit a preamble indicating transmission information for thesubsequent transmission interval (e.g., duration, TDD UL-DLconfiguration, etc.). The base station 105 may begin DL datatransmission 410 which may include data intended for multiple UEs 115and reference signals, including RSs 420. The UEs 115 may generateACK/NACK information 425 based on whether the received data blocks havebeen correctly decoded. The UEs 115 may also use the RSs 420 to generateCSI report 430. In one example, base station 105 may transmit downlinkdata (e.g., code-words, etc.) within duration t_(D) to the designatedUEs 115 and stop transmitting. The UEs 115 may wait an interval is afterthe completion of DL data transmission 410 and may then begin UL controlchannel transmissions 415. The interval is may be shorter than the CCAduration and may be a time period associated with the eCC (e.g., an eCCsymbol period), or may be skipped (e.g., no delay prior to UL controlchannel transmission 415), in some cases. During the control channeltransmissions, the UEs 115 may transmit ACK/NACK information 425 to thebase station 105 without performing a CCA. If the data transmissionincluded in DL data transmission 410 for a particular UE 115 decodes inerror, the UE 115 may send an explicit NACK in the UL control channeltransmission 415. In some cases, the UEs 115 may include CSI report 430with the ACK/NACK information. In some cases, each UE 115 may bedesignated non-interfering time or frequency resources for uplinkreporting (e.g., separate time-frequency blocks, interleaved frequencyresources, etc.). For instance, a first set of UEs 115 may transmit oninterleaved frequency resources during a first set of symbols, while asecond set of UEs 115 may transmit on interleaved frequency resourcesduring a second, subsequent set of symbols. The CSI report may includeCQI, PMI, RI, etc.

The control information (e.g., ACK/NACK, CSI, uplink resource request,etc.) transmitted in UL control channel transmission 415 may be mappedto resources of a dedicated control channel structure. For example, thecontrol information may be coded or replicated to generate N modulationsymbols, and the N modulation symbols may be modulated using N sequencesof M symbols to generate N sequences of M modulated control informationsymbols that are mapped to specific time-frequency resources of thecontrol channel structure. For example, ACK/NACK, CSI, and uplinkresource request information may be mapped to designated portions of thecontrol channel structure. In some examples, the control channelstructure may correspond to a control channel TTI including apredetermined number of eCC symbol periods (e.g., 1, 2, 4, 8, etc.).Each UE may have designated frequency resources (e.g., contiguoussubcarriers, interleaved subcarriers, etc.) within the control channelTTI, which may be determined implicitly (e.g., based on information inthe DL grant) or explicitly (e.g., based on UE-ID or configured usinghigher layers, etc.).

FIG. 4B illustrates an example of a fast feedback transmission scheme400-b for Channel feedback reporting for shared frequency spectrum inaccordance with various aspects of the present disclosure. Channelfeedback reporting may include ACK/NACK and CSI reports. Fast feedbacktransmission scheme 400-b may illustrate aspects of a transmissionbetween a UE 115 and a base station 105, as described above withreference to FIGS. 1-3B. Fast feedback transmission scheme 400-b mayinclude a DL CCA 405-a, DL data transmissions 410-a and 410-b, and ULcontrol channel transmission 415-a. The UE 115 may generate ACK/NACKinformation 425-a for data received in DL data transmission 410-a andmay include the ACK/NACK information 425-a in UL control channeltransmission 415-a. The DL data transmission 410-a may include RSs 420-awhich may be used by a UE 115 to generate a CSI report 430-a. The CSIreport 430-a may also be included in UL control channel transmission415-a.

In one example, the base station 105 may indicate an uplink and downlinkconfiguration that includes uplink TTIs 435 between two sets of downlinkTTIs. Similar to the above technique, a set of UEs 115 may wait aninterval is before transmitting UL control channel transmission 415-a,which may include ACK/NACK information 425-a. In some cases, the UEs 115may include a CSI report 430-a with the ACK/NACK information. In somecases, each UE 115 may determine which time and frequency resources willbe used by the other UEs 115 for CET transmissions and transmitaccordingly. In other cases, a base station 105 may designate to the UEs115 distinct, non-interfering time and frequency resources for CETtransmissions. At the completion of uplink TTIs 435, the base station105 may continue DL data transmissions 410-b.

FIG. 5 shows a block diagram of a wireless device 500 configured forchannel feedback reporting for shared frequency spectrum in accordancewith various aspects of the present disclosure. Wireless device 500 maybe an example of aspects of a UE 115 or base station 105 described withreference to FIGS. 1-4. Wireless device 500 may include a receiver 505,a feedback reporting manager 510, or a transmitter 515. Wireless device500 may also include a processor. Each of these components may be incommunication with each other.

The receiver 505 may receive information such as packets, user data, orcontrol information associated with various information channels (e.g.,control channels, data channels, and information related to CQI feedbackreporting for eCC, etc.). Information may be passed on to the feedbackreporting manager 510, and to other components of wireless device 500.In some examples, the receiver 505 may receive a data transmission fromthe eNB over the CC.

The feedback reporting manager 510 may communicate with an eNB using aCC over a shared frequency band, receive a data transmission from theeNB over the CC, determine ACK/NACK information for the datatransmission, and transmit the ACK/NACK information in a CCA exemptfeedback transmission to the eNB via the CC, wherein the ACK/NACKinformation is mapped to designated resources of an uplink controlchannel structure for the CCA-exempt feedback transmission. In somecases, the uplink control channel structure may comprise a subset offrequency resources of the CC.

The transmitter 515 may transmit signals received from other componentsof wireless device 500. In some examples, the transmitter 515 may becollocated with the receiver 505 in a transceiver module. Thetransmitter 515 may include a single antenna, or it may include aplurality of antennas. In some examples, the transmitter 515 maytransmit the ACK/NACK information in a CCA exempt feedback transmissionto the eNB via the CC, wherein the ACK/NACK information is mapped todesignated resources of an uplink control channel structure for theCCA-exempt feedback transmission. In some examples, the transmitter 515may transmit, in the CCA-exempt feedback transmission, the uplinkscheduling feedback or the CSI feedback. In some examples, thetransmitted CSI feedback comprises an indicator associated with thetarget MCS. In some examples, the indicator associated with the targetMCS comprises the channel quality delta. In some examples, the start ofthe CCA-exempt feedback transmission occurs less than a predeterminedCCA time period from an end of the data transmission. In some examples,the first CSI feedback comprises a wideband channel quality for afrequency range spanning the one or more channels.

FIG. 6 shows a block diagram of a wireless device 600 for channelfeedback reporting for CCs (e.g., eCC in standalone operation, etc.) inaccordance with various aspects of the present disclosure. Wirelessdevice 600 may be an example of aspects of a wireless device 500, a UE115, or a base station 105 described with reference to FIGS. 1-5.Wireless device 600 may include a receiver 505-a, a feedback reportingmanager 510-a, or a transmitter 515-a. Wireless device 600 may alsoinclude a processor. Each of these components may be in communicationwith each other. The feedback reporting manager 510-a may also include acommunications manager 605, and a feedback processor 610.

The receiver 505-a may receive information which may be passed on tofeedback reporting manager 510-a, and to other components of wirelessdevice 600. The feedback reporting manager 510-a may perform theoperations described with reference to FIG. 5. The transmitter 515-a maytransmit signals received from other components of wireless device 600.

The communications manager 605 may manage communications with an eNBusing a CC over a shared frequency band as described with reference toFIGS. 2-4. The communications manager 605 may also identify atransmission, from the eNB, reserving one or more channels of the sharedfrequency band for communication via the CC, the transmissionidentifying a TDD configuration for the CC over a specified timeduration. The CC may include an eCC configured for the UE in astandalone operation mode as described with reference to FIGS. 2-4.

The feedback manager 610 may determine ACK/NACK information for the datatransmission as described with reference to FIGS. 2-4. The feedbackprocessor 610 may also determine uplink scheduling feedback or CSIfeedback. The feedback processor 610 may also receive a feedbackconfiguration for providing feedback for transmissions via the CC,wherein the feedback configuration indicates providing the feedback inthe CCA-exempt feedback transmission, a CCA-compliant feedbacktransmission, or combinations thereof. The feedback processor 610 mayalso determine an uplink transmission window of one or more uplinktransmission windows during the specified time duration for transmittingthe first CSI feedback based at least in part on a timing characteristicof the uplink transmission window relative to the identified TTI. Thefeedback processor 610 may also perform a CSI feedback transmissionprocedure to transmit the first CSI feedback during the uplinktransmission window. In some examples, the CSI feedback transmissionprocedure comprises transmitting the first CSI feedback upon asuccessful reservation of the one or more channels based at least inpart on the first CCA-compliant feedback transmission procedure. In someexamples, the timing characteristic comprises the uplink transmissionwindow being within a time threshold of the identified TTI. In someexamples, the timing characteristic comprises the uplink transmissionwindow including the identified TTI. In some cases, CSI feedbacktransmissions may be aligned with a frame, subframe, or symbol boundary.In other cases, the CSI feedback may be transmitted asynchronously withradio boundaries.

FIG. 7 shows a block diagram 700 of a feedback reporting manager 510-bwhich may be a component of a wireless device 500 or a wireless device600 for channel feedback reporting for CCs (e.g., eCC in standaloneoperation, etc.) in accordance with various aspects of the presentdisclosure. The feedback reporting manager 510-b may be an example ofaspects of a feedback reporting manager 510 described with reference toFIGS. 5-6. The feedback reporting manager 510-b may include acommunications manager 605-a, and a feedback processor 610-a. Each ofthese modules may perform the functions described with reference to FIG.6. The feedback reporting manager 510-b may also include a channelquality manager 705, a channel monitor 710, and a feedback reporter 715.

The channel quality manager 705 may determine a target MCS for asubsequent data transmission based at least in part on channelmeasurements of one or more reference signals associated with the datatransmission as described with reference to FIGS. 2-4. The channelquality manager 705 may also determine a channel quality delta betweenthe current MCS and the target MCS. In some examples, the one or morereference signals comprise any of a CRS, a DM-RS, a UE-RS, orcombinations thereof. In some examples, the determining the target MCSfor the subsequent data transmission comprises estimating a quality of achannel from the eNB based at least in part on the CRS and the currentprecoding matrix. In some examples, the determining the target MCS forthe subsequent data transmission comprises estimating a quality of achannel from the eNB based at least in part on the CRS and hypotheticalcandidate precoding matrices. The channel quality manager 705 may alsoperform channel measurements for the one or more channels based at leastin part on the cyclical transmission pattern.

The channel monitor 710 may identify a current MCS for the datatransmission as described with reference to FIGS. 2-4. In some examples,the CSI feedback transmission procedure comprises determining that theone or more channels are busy during the first uplink TTI based at leastin part on the first CCA-compliant feedback transmission procedure. Thechannel monitor 710 may also identify a DRS configuration for the CC,the DRS configuration indicating a cyclical transmission pattern forreference signals transmitted in the one or more channels. The channelmonitor may additionally identify a TTI associated with transmittingfirst CSI feedback for a CC operating in a standalone operation modeover a shared frequency band based at least in part on a CSI feedbackconfiguration.

The feedback reporter 715 may be configured such that the CSI feedbacktransmission procedure may include performing a first CCA-compliantfeedback transmission procedure over the one or more channels during afirst uplink TTI of the uplink transmission window as described withreference to FIGS. 2-4. In some examples, the CSI feedback transmissionprocedure comprises performing a second CCA-compliant feedbacktransmission procedure over the one or more channels during a second,subsequent uplink TTI of the uplink transmission window. In some cases,the feedback reporter 715 may configured to report CSI feedback usingresources that are distinct and non-interfering with other devicestransmitting CSI reports.

FIG. 8 shows a diagram of a system 800 including a UE 115-c configuredfor channel feedback reporting for CCs (e.g., eCC in standaloneoperation, etc.) in accordance with various aspects of the presentdisclosure. System 800 may include UE 115-c, which may be an example ofa wireless device 500, a wireless device 600, a UE 115, or a basestation 105 described with reference to FIGS. 1, 2 and 5-7. UE 115-c mayinclude a feedback reporting module 810, which may be an example of afeedback reporting manager 510 described with reference to FIGS. 5-7. UE115-c may also include components for bi-directional voice and datacommunications including components for transmitting communications andcomponents for receiving communications. For example, UE 115-c maycommunicate bi-directionally with base station 105-b or UE 115-d.

UE 115-c may also include a processor 805, and memory 815 (includingsoftware (SW)) 820, a transceiver 835, and one or more antenna(s) 840,each of which may communicate, directly or indirectly, with one another(e.g., via buses 845). The transceiver 835 may communicatebi-directionally, via the antenna(s) 840 or wired or wireless links,with one or more networks, as described above. For example, thetransceiver 835 may communicate bi-directionally with a base station 105or another UE 115. The transceiver 835 may include a modem to modulatethe packets and provide the modulated packets to the antenna(s) 840 fortransmission, and to demodulate packets received from the antenna(s)840. While UE 115-c may include a single antenna 840, UE 115-c may alsohave multiple antennas 840 capable of concurrently transmitting orreceiving multiple wireless transmissions.

The memory 815 may include random access memory (RAM) and read onlymemory (ROM). The memory 815 may store computer-readable,computer-executable software/firmware code 820 including instructionsthat, when executed, cause the processor 805 to perform variousfunctions described herein (e.g., CQI feedback reporting for eCC, etc.).Alternatively, the software/firmware code 820 may not be directlyexecutable by the processor 805 but cause a computer (e.g., whencompiled and executed) to perform functions described herein. Theprocessor 805 may include an intelligent hardware device, (e.g., acentral processing unit (CPU), a microcontroller, an applicationspecific integrated circuit (ASIC), etc.)

FIG. 9 shows a diagram of a system 900 including a base station 105-cconfigured for managing and processing channel feedback for CCs (e.g.,eCCs in standalone operation, etc.) in accordance with various aspectsof the present disclosure. System 900 may include base station 105-c,which may be an example of a base station 105 described with referenceto FIGS. 1, 2 and 6-8. Base station 105-c may configure UEs 115 forchannel feedback reporting for CCs and process channel feedback receivedfrom UEs 115. For example, base station 105-c may determine transmissionstrategies, MCSs, and the like for future communications with UE 115based on the channel feedback. Base station 105-c may also includecomponents for bi-directional voice and data communications includingcomponents for transmitting communications and components for receivingcommunications. For example, base station 105-c may communicatebi-directionally with base station 105-d, base station 105-e, UE 115-e,or UE 115-f.

In some cases, base station 105-c may have one or more wired backhaullinks. Base station 105-c may have a wired backhaul link (e.g., 51interface, etc.) to the core network 130. Base station 105-c may alsocommunicate with other base stations 105, such as base station 105-d andbase station 105-e via inter-base station backhaul links (e.g., an X2interface). Each of the base stations 105 may communicate with UEs 115using the same or different wireless communications technologies. Insome cases, base station 105-c may communicate with other base stationssuch as 105-d or 105-e utilizing base station communications module 925.In some examples, base station communications module 925 may provide anX2 interface within a Long Term Evolution (LTE)/LTE-A wirelesscommunication network technology to provide communication between someof the base stations 105. In some examples, base station 105-c maycommunicate with other base stations through core network 130. In somecases, base station 105-c may communicate with the core network 130through network communications module 930.

The base station 105-c may include a processor 905, a base stationfeedback processor 910, memory 915 (including software (SW) 920),transceiver 935, and antenna(s) 940, which each may be in communication,directly or indirectly, with one another (e.g., over bus system 945).The transceivers 935 may be configured to communicate bi-directionally,via the antenna(s) 940, with the UEs 115, which may be multi-modedevices. The transceiver 935 (or other components of the base station105-c) may also be configured to communicate bi-directionally, via theantennas 940, with one or more other base stations (not shown). Thetransceiver 935 may include a modem configured to modulate the packetsand provide the modulated packets to the antennas 940 for transmission,and to demodulate packets received from the antennas 940. The basestation 105-c may include multiple transceivers 935, each with one ormore associated antennas 940. The transceiver may be an example of acombined receiver 505 and transmitter 515 of FIG. 5.

The base station feedback processor 910 may be used to configure andsupport feedback reporting (e.g., in control information, etc.) asdescribed with respect to FIGS. 2-8. For instance, the base stationfeedback processor 910 may be used to assign CSI reporting windows to aUE 115. In some cases, the base station feedback processor 910 may beused to schedule multiple UEs 115 for CSI reporting. For instance, thebase station feedback processor 910 may be used to assign distinct,non-interfering time and frequency resources (e.g., separatetime-frequency blocks, interleaved frequency resources, etc.) to a setof UEs 115. The assigned resources may be used for fast feedback by theUEs 115. For example, the UEs 115 may use this scheduling to coordinateCET transmission to base station 105-c as discussed with reference toFIGS. 4A and 4B. Furthermore, the base station feedback processor 910may be used to transmit (e.g., via transceivers 935) aperiodic reportingtrigger indicators and to map reference signals corresponding to thetriggering. In some cases, the base station feedback processor 910 maytransmit reference symbols semi-statically using configured periodictime and frequency locations. For instance, the reference signals mayonly be dynamically available based on base station transmissions forwhich a CCA is successful. In some cases, the base station feedbackprocessor 910 may send CSI-RSs on subframes in which the base stationfeedback processor sends aperiodic feedback requests. The base stationfeedback processor 910 may signal the presence of CSI-RSs in downlinkgrants so that other UEs 115 may perform PDSCH rate matching.

The memory 915 may include RAM and ROM. The memory 915 may also storecomputer-readable, computer-executable software code 920 containinginstructions that are configured to, when executed, cause the processor905 to perform various functions described herein (e.g., CQI feedbackreporting for eCC, selecting coverage enhancement techniques, callprocessing, database management, message routing, etc.). Alternatively,the software 920 may not be directly executable by the processor 905 butbe configured to cause the computer, e.g., when compiled and executed,to perform functions described herein. The processor 905 may include anintelligent hardware device, e.g., a CPU, a microcontroller, an ASIC,etc. The processor 905 may include various special purpose processorssuch as encoders, queue processing modules, base band processors, radiohead controllers, digital signal processor (DSPs), and the like.

The base station communications module 925 may manage communicationswith other base stations 105. In some cases, a communications managementmodule may include a controller or scheduler for controllingcommunications with UEs 115 in cooperation with other base stations 105.For example, the base station communications module 925 may coordinatescheduling for transmissions to UEs 115 for various interferencemitigation techniques such as beamforming or joint transmission.

The components of wireless device 500, wireless device 600, and feedbackreporting manager 510-b may, individually or collectively, beimplemented with at least one ASIC adapted to perform some or all of theapplicable functions in hardware. Alternatively, the functions may beperformed by one or more other processing units (or cores), on at leastone IC. In other examples, other types of integrated circuits may beused (e.g., Structured/Platform ASICs, a field programmable gate array(FPGA), or another semi-custom IC), which may be programmed in anymanner known in the art. The functions of each unit may also beimplemented, in whole or in part, with instructions embodied in amemory, formatted to be executed by one or more general orapplication-specific processors.

FIG. 10 shows a flowchart illustrating a method 1000 for channelfeedback reporting for CCs (e.g., eCC in standalone operation, etc.) inaccordance with various aspects of the present disclosure. Theoperations of method 1000 may be implemented by a device, such as a UE115 or base station 105, or its components as described with referenceto FIGS. 1-9. For example, the operations of method 1000 may beperformed by the feedback reporting manager 510 as described withreference to FIGS. 5-8. In some examples, a device may execute a set ofcodes to control the functional elements of the device to perform thefunctions described below. Additionally or alternatively, the device mayperform aspects the functions described below using special-purposehardware.

At block 1005, the device may communicate with an eNB over a frequencychannel of a shared frequency band as described with reference to FIGS.2-4. In certain examples, the operations of block 1005 may be performedby the communications manager 605 as described with reference to FIG. 6.

At block 1010, the device may receive a data transmission from the eNBover the frequency channel of the shared frequency band as describedwith reference to FIGS. 2-4. In certain examples, the operations ofblock 1010 may be performed by the receiver 505 as described withreference to FIG. 5.

At block 1015, the device may determine ACK/NACK information for thedata transmission as described with reference to FIGS. 2-4. In certainexamples, the operations of block 1015 may be performed by the feedbackprocessor 610 as described with reference to FIG. 6.

At block 1020, the device may transmit the ACK/NACK information in a CCAexempt feedback transmission to the eNB via the frequency channel of theshared frequency band, wherein the ACK/NACK information is mapped todesignated resources of an uplink control channel structure for theCCA-exempt feedback transmission as described with reference to FIGS.2-4. In certain examples, the operations of block 1020 may be performedby the transmitter 515 as described with reference to FIG. 5.

FIG. 11 shows a flowchart illustrating a method 1100 for channelfeedback reporting for CCs (e.g., eCC in standalone operation, etc.) inaccordance with various aspects of the present disclosure. Theoperations of method 1100 may be implemented by a device, such as a UE115 or base station 105, or its components as described with referenceto FIGS. 1-9. For example, the operations of method 1100 may beperformed by the feedback reporting manager 510 as described withreference to FIGS. 5-8. In some examples, a device may execute a set ofcodes to control the functional elements of the device to perform thefunctions described below. Additionally or alternatively, the device mayperform aspects the functions described below using special-purposehardware. The method 1100 may also incorporate aspects of method 1000 ofFIG. 10.

At block 1105, the device may communicate with an eNB using a CC over ashared frequency band as described with reference to FIGS. 2-4. Incertain examples, the operations of block 1105 may be performed by thecommunications manager 605 as described with reference to FIG. 6.

At block 1110, the device may receive a data transmission from the eNBover the CC as described with reference to FIGS. 2-4. In certainexamples, the operations of block 1110 may be performed by the receiver505 as described with reference to FIG. 5.

At block 1115, the device may determine ACK/NACK information for thedata transmission as described with reference to FIGS. 2-4. In certainexamples, the operations of block 1115 may be performed by the feedbackprocessor 610 as described with reference to FIG. 6.

At block 1120, the device may determine uplink scheduling feedback orCSI feedback as described with reference to FIGS. 2-4. Determining theCSI feedback may include determining a target MCS for a subsequentuplink data transmission based at least in part on channel measurementsof one or more reference signals associated with the data transmissionIn certain examples, the operations of block 1120 may be performed bythe feedback processor 610 and/or the channel quality manager 705 asdescribed with reference to FIGS. 6 and 7.

At block 1125, the device may transmit the ACK/NACK information in a CCAexempt feedback transmission to the eNB via the CC, wherein the ACK/NACKinformation is mapped to designated resources of an uplink controlchannel structure for the CCA-exempt feedback transmission as describedwith reference to FIGS. 2-4. In some cases, the device may transmit, inthe CCA-exempt feedback transmission, the uplink scheduling feedback orthe CSI feedback as described with reference to FIGS. 2-4. In somecases, the transmitted CSI feedback comprises an indicator associatedwith the determined target MCS. In certain examples, the operations ofblock 1125 may be performed by the transmitter 515 as described withreference to FIG. 5.

FIG. 12 shows a flowchart illustrating a method 1200 for channelfeedback reporting for CCs (e.g., eCC in standalone operation, etc.) inaccordance with various aspects of the present disclosure. Theoperations of method 1200 may be implemented by a device, such as a UE115 or base station 105, or its components as described with referenceto FIGS. 1-9. For example, the operations of method 1200 may beperformed by the feedback reporting manager 510 as described withreference to FIGS. 5-8. In some examples, a device may execute a set ofcodes to control the functional elements of the device to perform thefunctions described below. Additionally or alternatively, the device mayperform aspects the functions described below using special-purposehardware. The method 1200 may also incorporate aspects of methods 1000,and 1100 of FIGS. 10-11.

At block 1205, the device may identify a TTI associated withtransmitting first CSI feedback for a CC operating in a standaloneoperation mode over a shared frequency band based at least in part on aCSI feedback configuration as described with reference to FIGS. 2-4. Incertain examples, the operations of block 1205 may be performed by thechannel monitor 720 as described with reference to FIG. 7.

At block 1210, the device may identify a transmission, from the eNB,reserving one or more channels of the shared frequency band forcommunication via the CC, the transmission identifying a TDDconfiguration for the CC over a specified time duration as describedwith reference to FIGS. 2-4. In certain examples, the operations ofblock 1210 may be performed by the communications manager 605 asdescribed with reference to FIG. 6.

At block 1215, the device may determine an uplink transmission window ofone or more uplink transmission windows during the specified timeduration for transmitting the first CSI feedback based at least in parton a timing characteristic of the uplink transmission window relative tothe identified TTI as described with reference to FIGS. 2-4. In certainexamples, the operations of block 1215 may be performed by the feedbackprocessor 610 as described with reference to FIG. 6.

At block 1220, the device may perform a CSI feedback transmissionprocedure to transmit the first CSI feedback during the uplinktransmission window as described with reference to FIGS. 2-4. In certainexamples, the operations of block 1220 may be performed by the feedbackprocessor 610 as described with reference to FIG. 6.

Thus, methods 1000, 1100, and 1200 may provide for CQI feedbackreporting for eCC. It should be noted that methods 1000, 1100, and 1200describe possible implementation, and that the operations and the stepsmay be rearranged or otherwise modified such that other implementationsare possible. In some examples, aspects from two or more of the methods1000, 1100, and 1200 may be combined.

The description herein provides examples, and is not limiting of thescope, applicability, or examples set forth in the claims. Changes maybe made in the function and arrangement of elements discussed withoutdeparting from the scope of the disclosure. Various examples may omit,substitute, or add various procedures or components as appropriate.Also, features described with respect to some examples may be combinedin other examples.

Techniques described herein may be used for various wirelesscommunications systems such as code division multiple access (CDMA),time division multiple access (TDMA), frequency division multiple access(FDMA), orthogonal frequency division multiple access (OFDMA), singlecarrier frequency division multiple access (SC-FDMA), and other systems.The terms “system” and “network” are often used interchangeably. A codedivision multiple access (CDMA) system may implement a radio technologysuch as CDMA2000, Universal Terrestrial Radio Access (UTRA), etc.CDMA2000 covers IS-2000, IS-95, and IS-856 standards. IS-2000 Releases 0and A are commonly referred to as CDMA2000 1X, 1X, etc. IS-856 (TIA-856)is commonly referred to as CDMA2000 1xEV-DO, High Rate Packet Data(HRPD), etc. UTRA includes Wideband CDMA (WCDMA) and other variants ofCDMA. A time division multiple access (TDMA) system may implement aradio technology such as Global System for Mobile Communications (GSM).An orthogonal frequency division multiple access (OFDMA) system mayimplement a radio technology such as Ultra Mobile Broadband (UMB),Evolved UTRA (E-UTRA), IEEE 802.11 (Wi-Fi), IEEE 802.16 (WiMAX), IEEE802.20, Flash-OFDM, etc. UTRA and E-UTRA are part of Universal MobileTelecommunications system (UMTS). 3GPP Long Term Evolution (LTE) andLIE-advanced (LTE-a) are new releases of Universal

Mobile Telecommunications System (UMTS) that use E-UTRA. UTRA, E-UTRA,Universal Mobile Telecommunications System (UMTS), LIE, L1E-a, andGlobal System for Mobile communications (GSM) are described in documentsfrom an organization named “3rd Generation Partnership Project” (3GPP).CDMA2000 and UMB are described in documents from an organization named“3rd Generation Partnership Project 2” (3GPP2). The techniques describedherein may be used for the systems and radio technologies mentionedabove as well as other systems and radio technologies. The descriptionherein, however, describes an LTE system for purposes of example, andLTE terminology is used in much of the description above, although thetechniques are applicable beyond LTE applications.

In LTE/LTE-a networks, including such networks described herein, theterm evolved node B (eNB) may be generally used to describe the basestations. The wireless communications system or systems described hereinmay include a heterogeneous LTE/LTE-a network in which different typesof eNBs provide coverage for various geographical regions. For example,each eNB or base station may provide communication coverage for a macrocell, a small cell, or other types of cell. The term “cell” is a 3GPPterm that can be used to describe a base station, a carrier or componentcarrier associated with a base station, or a coverage area (e.g.,sector, etc.) of a carrier or base station, depending on context.

Base stations may include or may be referred to by those skilled in theart as a base transceiver station, a radio base station, an accesspoint, a radio transceiver, a NodeB, eNodeB (eNB), Home NodeB, a HomeeNodeB, or some other suitable terminology. The geographic coverage areafor a base station may be divided into sectors making up only a portionof the coverage area. The wireless communications system or systemsdescribed herein may include base stations of different types (e.g.,macro or small cell base stations). The UEs described herein may be ableto communicate with various types of base stations and network equipmentincluding macro eNBs, small cell eNBs, relay base stations, and thelike. There may be overlapping geographic coverage areas for differenttechnologies.

A macro cell generally covers a relatively large geographic area (e.g.,several kilometers in radius) and may allow unrestricted access by UEswith service subscriptions with the network provider. A small cell is alower-powered base station, as compared with a macro cell, that mayoperate in the same or different (e.g., licensed, unlicensed, etc.)frequency bands as macro cells. Small cells may include pico cells,femto cells, and micro cells according to various examples. A pico cell,for example, may cover a small geographic area and may allowunrestricted access by UEs with service subscriptions with the networkprovider. A femto cell may also cover a small geographic area (e.g., ahome) and may provide restricted access by UEs having an associationwith the femto cell (e.g., UEs in a closed subscriber group (CSG), UEsfor users in the home, and the like). An eNB for a macro cell may bereferred to as a macro eNB. An eNB for a small cell may be referred toas a small cell eNB, a pico eNB, a femto eNB, or a home eNB. An eNB maysupport one or multiple (e.g., two, three, four, and the like) cells(e.g., component carriers). A UE may be able to communicate with varioustypes of base stations and network equipment including macro eNBs, smallcell eNBs, relay base stations, and the like.

The wireless communications system or systems described herein maysupport synchronous or asynchronous operation. For synchronousoperation, the base stations may have similar frame timing, andtransmissions from different base stations may be approximately alignedin time. For asynchronous operation, the base stations may havedifferent frame timing, and transmissions from different base stationsmay not be aligned in time. The techniques described herein may be usedfor either synchronous or asynchronous operations.

The downlink transmissions described herein may also be called forwardlink transmissions while the uplink transmissions may also be calledreverse link transmissions. Each communication link describedherein—including, for example, wireless communications system 100 andwireless communications subsystem 200 of FIGS. 1 and 2—may include oneor more carriers, where each carrier may be a signal made up of multiplesub-carriers (e.g., waveform signals of different frequencies). Eachmodulated signal may be sent on a different sub-carrier and may carrycontrol information (e.g., reference signals, control channels, etc.),overhead information, user data, etc. The communication links describedherein (e.g., communication links 125 of FIG. 1) may transmitbidirectional communications using frequency division duplex (FDD)(e.g., using paired spectrum resources) or TDD operation (e.g., usingunpaired spectrum resources). Frame structures may be defined forfrequency division duplex (FDD) (e.g., frame structure type 1) and TDD(e.g., frame structure type 2).

The description set forth herein, in connection with the appendeddrawings, describes example configurations and does not represent allthe examples that may be implemented or that are within the scope of theclaims. The term “exemplary” used herein means “serving as an example,instance, or illustration,” and not “preferred” or “advantageous overother examples.” The detailed description includes specific details forthe purpose of providing an understanding of the described techniques.These techniques, however, may be practiced without these specificdetails. In some instances, well-known structures and devices are shownin block diagram form in order to avoid obscuring the concepts of thedescribed examples.

In the appended figures, similar components or features may have thesame reference label. Further, various components of the same type maybe distinguished by following the reference label by a dash and a secondlabel that distinguishes among the similar components. If just the firstreference label is used in the specification, the description isapplicable to any one of the similar components having the same firstreference label irrespective of the second reference label.

Information and signals described herein may be represented using any ofa variety of different technologies and techniques. For example, data,instructions, commands, information, signals, bits, symbols, and chipsthat may be referenced throughout the above description may berepresented by voltages, currents, electromagnetic waves, magneticfields or particles, optical fields or particles, or any combinationthereof.

The various illustrative blocks and modules described in connection withthe disclosure herein may be implemented or performed with ageneral-purpose processor, a DSP, an ASIC, an FPGA or other programmablelogic device, discrete gate or transistor logic, discrete hardwarecomponents, or any combination thereof designed to perform the functionsdescribed herein. A general-purpose processor may be a microprocessor,but in the alternative, the processor may be any conventional processor,controller, microcontroller, or state machine. A processor may also beimplemented as a combination of computing devices (e.g., a combinationof a digital signal processor (DSP) and a microprocessor, multiplemicroprocessors, one or more microprocessors in conjunction with a DSPcore, or any other such configuration).

The functions described herein may be implemented in hardware, softwareexecuted by a processor, firmware, or any combination thereof. Ifimplemented in software executed by a processor, the functions may bestored on or transmitted over as one or more instructions or code on acomputer-readable medium. Other examples and implementations are withinthe scope and spirit of the disclosure and appended claims. For example,due to the nature of software, functions described above can beimplemented using software executed by a processor, hardware, firmware,hardwiring, or combinations of any of these. Features implementingfunctions may also be physically located at various positions, includingbeing distributed such that portions of functions are implemented atdifferent physical locations. As used herein, including in the claims,the term “and/or,” when used in a list of two or more items, means thatany one of the listed items can be employed by itself, or anycombination of two or more of the listed items can be employed. Forexample, if a composition is described as containing components A, B,and/or C, the composition can contain A alone; B alone; C alone; A and Bin combination; A and C in combination; B and C in combination; or A, B,and C in combination. Also, as used herein, including in the claims,“or” as used in a list of items (for example, a list of items prefacedby a phrase such as “at least one of” or “one or more of”) indicates adisjunctive list such that, for example, a list of “at least one of A,B, or C” means A or B or C or AB or AC or BC or ABC (i.e., A and B andC).

Computer-readable media includes both non-transitory computer storagemedia and communication media including any medium that facilitatestransfer of a computer program from one place to another. Anon-transitory storage medium may be any available medium that can beaccessed by a general purpose or special purpose computer. By way ofexample, and not limitation, non-transitory computer-readable media cancomprise RANI, ROM, electrically erasable programmable read only memory(EEPROM), compact disk (CD) ROM or other optical disk storage, magneticdisk storage or other magnetic storage devices, or any othernon-transitory medium that can be used to carry or store desired programcode means in the form of instructions or data structures and that canbe accessed by a general-purpose or special-purpose computer, or ageneral-purpose or special-purpose processor. Also, any connection isproperly termed a computer-readable medium. For example, if the softwareis transmitted from a website, server, or other remote source using acoaxial cable, fiber optic cable, twisted pair, digital subscriber line(DSL), or wireless technologies such as infrared, radio, and microwave,then the coaxial cable, fiber optic cable, twisted pair, digitalsubscriber line (DSL), or wireless technologies such as infrared, radio,and microwave are included in the definition of medium. Disk and disc,as used herein, include CD, laser disc, optical disc, digital versatiledisc (DVD), floppy disk and Blu-ray disc where disks usually reproducedata magnetically, while discs reproduce data optically with lasers.Combinations of the above are also included within the scope ofcomputer-readable media.

The description herein is provided to enable a person skilled in the artto make or use the disclosure. Various modifications to the disclosurewill be readily apparent to those skilled in the art, and the genericprinciples defined herein may be applied to other variations withoutdeparting from the scope of the disclosure. Thus, the disclosure is notto be limited to the examples and designs described herein but is to beaccorded the broadest scope consistent with the principles and novelfeatures disclosed herein.

What is claimed is:
 1. A method of wireless communication at a userequipment (UE), comprising: communicating with an evolved node B (eNB)over a frequency channel of a shared frequency band; receiving a datatransmission from the eNB over the frequency channel of the sharedfrequency band; determining acknowledgement/negative acknowledgement(ACK/NACK) information for the data transmission; and transmitting theACK/NACK information in a clear channel assessment (CCA) exempt feedbacktransmission to the eNB via the frequency channel of the sharedfrequency band, wherein the ACK/NACK information is mapped to designatedresources of an uplink control channel structure for the CCA-exemptfeedback transmission.
 2. The method of claim 1, further comprising:determining uplink scheduling feedback or channel state information(CSI) feedback; and transmitting, in the CCA-exempt feedbacktransmission, the uplink scheduling feedback or the CSI feedback.
 3. Themethod of claim 2, further comprising: determining a target modulationand coding scheme (MCS) for a subsequent data transmission based atleast in part on channel measurements of one or more reference signalsassociated with the data transmission; and wherein the transmitted CSIfeedback comprises an indicator associated with the target MCS.
 4. Themethod of claim 3, further comprising: identifying a current MCS for thedata transmission; and determining a channel quality delta between thecurrent MCS and the target MCS, wherein the indicator associated withthe target MCS comprises the channel quality delta.
 5. The method ofclaim 3, wherein the one or more reference signals comprise any of acell-specific reference signal (CRS), a demodulation reference signal(DM-RS), a UE-specific reference signal (UE-RS), or combinationsthereof.
 6. The method of claim 5, wherein the determining the targetMCS for the subsequent data transmission comprises estimating a qualityof a channel from the eNB based at least in part on the CRS and anidentified precoding matrix for the data transmission.
 7. The method ofclaim 1, wherein the uplink control channel structure comprises a subsetof frequency resources of the frequency channel of the shared frequencyband.
 8. The method of claim 1, wherein the start of the CCA-exemptfeedback transmission occurs less than a predetermined CCA time periodfrom an end of the data transmission.
 9. The method of claim 1, whereinthe frequency channel of the shared frequency band comprises an enhancedcomponent carrier (eCC) configured for the UE in a standalone operationmode.
 10. The method of claim 1, further comprising: receiving afeedback configuration for providing feedback for transmissions over thefrequency channel of the shared frequency band, wherein the feedbackconfiguration indicates providing the feedback in the CCA-exemptfeedback transmission, a CCA-compliant feedback transmission, orcombinations thereof.
 11. A method of wireless communication at a userequipment (UE), comprising: identifying a transmission time interval(TTI) associated with transmitting first channel state information (CSI)feedback for a component carrier (CC) operating in a standaloneoperation mode over a shared frequency band based at least in part on aCSI feedback configuration; identifying a transmission, from the evolvednode B (eNB), reserving one or more channels of the shared frequencyband for communication via the CC, the transmission identifying a timedivision duplex (TDD) configuration for the CC over a specified timeduration; determining an uplink transmission window of one or moreuplink transmission windows during the specified time duration fortransmitting the first CSI feedback based at least in part on a timingcharacteristic of the uplink transmission window relative to theidentified TTI; and performing a CSI feedback transmission procedure totransmit the first CSI feedback during the uplink transmission window.12. The method of claim 11, wherein the CSI feedback transmissionprocedure comprises performing a first clear channel assessment(CCA)-compliant feedback transmission procedure over the one or morechannels during a first uplink TTI of the uplink transmission window.13. The method of claim 12, wherein the CSI feedback transmissionprocedure comprises transmitting the first CSI feedback upon asuccessful reservation of the one or more channels based at least inpart on the first CCA-compliant feedback transmission procedure.
 14. Themethod of claim 12, wherein the CSI feedback transmission procedurecomprises determining that the one or more channels are busy during thefirst uplink TTI based at least in part on the first CCA-compliantfeedback transmission procedure; and the CSI feedback transmissionprocedure comprises performing a second CCA-compliant feedbacktransmission procedure over the one or more channels during a second,subsequent uplink TTI of the uplink transmission window.
 15. The methodof claim 11, further comprising: identifying a discovery referencesignal (DRS) configuration for the CC, the DRS configuration indicatinga cyclical transmission pattern for reference signals transmitted in theone or more channels; and performing channel measurements for the one ormore channels based at least in part on the cyclical transmissionpattern.
 16. The method of claim 11, wherein the first CSI feedbackcomprises a wideband channel quality for a frequency range spanning theone or more channels.
 17. The method of claim 11, wherein the timingcharacteristic comprises the uplink transmission window being within atime threshold of the identified TTI.
 18. The method of claim 11,wherein the timing characteristic comprises the uplink transmissionwindow including the identified TTI.
 19. An apparatus for wirelesscommunication, comprising: a processor; memory in electroniccommunication with the processor; and instructions stored in the memoryand operable, when executed by the processor, to cause the apparatus to:communicate with an evolved node B (eNB) over a frequency channel of ashared frequency band; receive a data transmission from the eNB over thefrequency channel of the shared frequency band; determineacknowledgement/ negative acknowledgement (ACK/NACK) information for thedata transmission; and transmit the ACK/NACK information in a clearchannel assessment (CCA) exempt feedback transmission to the eNB via thefrequency channel of the shared frequency band, wherein the ACK/NACKinformation is mapped to designated resources of an uplink controlchannel structure for the CCA-exempt feedback transmission.
 20. Theapparatus of claim 19, wherein the instructions are operable to causeto: determine uplink scheduling feedback or channel state information(CSI) feedback; and transmit, in the clear channel assessment(CCA)-exempt feedback transmission, the uplink scheduling feedback orthe CSI feedback.
 21. The apparatus of claim 20, wherein theinstructions are operable to cause to: determine a target modulation andcoding scheme (MCS) for a subsequent data transmission based at least inpart on channel measurements of one or more reference signals associatedwith the data transmission; and wherein the transmitted CSI feedbackcomprises an indicator associated with the target MCS.
 22. The apparatusof claim 21, wherein the instructions are operable to cause to: identifya current MCS for the data transmission; and determine a channel qualitydelta between the current MCS and the target MCS, wherein the indicatorassociated with the target MCS comprises the channel quality delta. 23.The apparatus of claim 21, wherein the one or more reference signalscomprise any of a cell-specific reference signal (CRS), a demodulationreference signal (DM-RS), a UE-specific reference signal (UE-RS), orcombinations thereof.
 24. The apparatus of claim 23, wherein thedetermining the target MCS for the subsequent data transmissioncomprises estimating a quality of a channel from the eNB based at leastin part on the CRS and an identified precoding matrix for the datatransmission.
 25. The apparatus of claim 19, wherein the instructionsare operable to cause to: receive a feedback configuration for providingfeedback for transmissions over the frequency channel of the sharedfrequency band, wherein the feedback configuration indicates providingthe feedback in the CCA-exempt feedback transmission, a CCA-compliantfeedback transmission, or combinations thereof.
 26. An apparatus forwireless communication, comprising: a processor; memory in electroniccommunication with the processor; and instructions stored in the memoryand operable, when executed by the processor, to cause the apparatus to:identify a transmission time interval (TTI) associated with transmittingfirst channel state information (CSI) feedback for a component carrier(CC) operating in a standalone operation mode over a shared frequencyband based at least in part on a CSI feedback configuration; identify atransmission, from the eNB, reserving one or more channels of the sharedfrequency band for communication via the CC, the transmissionidentifying a time division duplex (TDD) configuration for the CC over aspecified time duration; determine an uplink transmission window of oneor more uplink transmission windows during the specified time durationfor transmitting the first CSI feedback based at least in part on atiming characteristic of the uplink transmission window relative to theidentified TTI; and perform a CSI feedback transmission procedure totransmit the first CSI feedback during the uplink transmission window.27. The apparatus of claim 26, wherein the CSI feedback transmissionprocedure comprises performing a first clear channel assessment(CCA)-compliant feedback transmission procedure over the one or morechannels during a first uplink TTI of the uplink transmission window.28. The apparatus of claim 27, wherein the CSI feedback transmissionprocedure comprises transmitting the first CSI feedback upon asuccessful reservation of the one or more channels based at least inpart on the first CCA-compliant feedback transmission procedure.
 29. Theapparatus of claim 27, wherein the CSI feedback transmission procedurecomprises determining that the one or more channels are busy during thefirst uplink TTI based at least in part on the first CCA-compliantfeedback transmission procedure; and the CSI feedback transmissionprocedure comprises performing a second CCA-compliant feedbacktransmission procedure over the one or more channels during a second,subsequent uplink TTI of the uplink transmission window.
 30. Theapparatus of claim 26, wherein the instructions are operable to causeto: identify a discovery reference signal (DRS) configuration for theCC, the DRS configuration indicating a cyclical transmission pattern forreference signals transmitted in the one or more channels; and performchannel measurements for the one or more channels based at least in parton the cyclical transmission pattern.